Which of the following pulmonary changes is characteristically observed in chronic cigarette smokers?

### Why this is right - **A** is correct: reduced forced expiratory volume in one second is listed as a spirometry change in active smokers. - **B** is correct: the decreased ratio is described as indicating airflow obstruction. - **C** is correct: destruction of alveolar walls is a structural change associated with emphysema. ### The concept Spirometry measures breathing performance, including the volume expelled during the first second of a forced breath out and the total forced volume. Structural changes are different: destruction of alveolar walls affects the small air sacs, while airway-wall thickening reflects chronic inflammation. The material describes a loss, not an increase, in lung elasticity. ### The other options - **D. Increased lung elasticity**: The material describes loss of lung elasticity and air trapping, so an increase is contrary to the stated finding. ### Terms - **FEV1**: Forced expiratory volume in one second, the air expelled in the first second of a forced breath out. - **FVC**: Forced vital capacity, the total volume forcibly breathed out after a full breath in. - **Alveolar wall**: The wall of a small lung air sac involved in gas exchange. ### Remember The listed smoking-related changes include lower spirometry measures and structural damage, not improved elasticity.